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The crisis in orthodontia Part I 2. Tissue changes during retention. Skogborg's septotomy
(Contint&
fr,om
pogP
466,
,4pril)
F
because, OR my experiments I hare preferred win, (1 the teeth of monkeys. as I pointed out in 1917.’ their structure is wry similar to that of humarl direct transmisteeth, because the straight course of’ their roots guarantees sion of ort,hodont,ic forces to the bone, and because of the analogous anatomic relations that exist between their teeth and t,he compact a.nd spongy jaw honca and those of man. gives a similar reason for losing rrionke~~s for his experiments: Marshall2 “The teeth of macacus rhesus show certain similarities to the trrth of mm not only in gross and microscopic anatomic: features. . .‘I These same argument,s influenced me also in the seleet,ion of the animals that were wed to study tissue changes (luring rct,rntion. These finclings which were reported briefly in 1913” shall now be reported in a more rxtrnsiw form. The experiment included four teeth and leads through a number of stages of transformation and retrograde changes back almost to the original lamellous bony structure. The following description of the ret rogratlr changes in the bone tlurill~ the period of retention Aarts out with the arrangement of t,he hone which is the result, of gent,le intermittent. forces as described in thv first chapter of t,his paper.$ Just as in this previous report I am showing first a general view picture of each one of t~he mored deciduous t,reth to illustrate the validity of findings in intact deciduous te&h ; by illustrating a control tooth and by using a uniform magnification (25 times) for wrrrsponding specimens, it ih possible to study the retrograde transformation during t,he period of retelltion and t,he narrowing of the bone which had been widened durirlg the periotl of active movement, by a new formation of ostcoplrytes. This gra.dual narrowing and functional transformation of the bone (‘an be plainly seen on teeth that have been retained rigidly as well as on teeth which have been subject lo the full influence of function ; however. we shall see that the extent of tjhcse changes depends largelyupon the degree of functional st.imulus. Jn jnimobilizetl. rigitlty rrtainetl trctlr the retrogratle *From the Department of Orthodontia of the tTranslated from Zeitsclw@t fiir GtomntoEo~gic. Schwarzenberg, Vienna and Berlin. ~INTmN.~T. J. ORTH. I!): 1206 (Fig. 6 ), l!l:I::. 5-1”
Dental Nos.
Institute of the CTniveraity 7 and 8, 1933, published by
of Vienna. Tirban and
transformation is less extensive than in teeth that have been subject to funct.ional stimulation. This process of transformation leads from the arrangemeat of the trabeculae parallel to the direction of force back to the arrangement parallel to the long axis of the tooth with lamellated structure of the bone and new Haversian canals. These pictures are very instructive, since the changes during retention are governed by individual requirements and endogenous forces and not by any ot,her influences or exogenous forces. As I stated in the first chapter, each active influence exerted upon the bone by means of appliances produces only relative biologic changes. This “It may be saitl has also been clearly recognized and laid down by IIellman:4
A
RP C C P %E
a
Fig. Fig.
1.
I.-General view picture of mandibular incisor wrtelztion. Direction of movement indicated by arrow. tions due perhaps to beginning shedding. C, cementurn resorption on the lingual side; ZK, germ of permanent Fig. S.-General view picture of mandibular incisor, tional stimulatiw. No evidence of shedding: direction cementurn ; A, osteoid bone, arranged in the direction of LK, germ of permanent tooth.
Fig.
2.
; magnification 8 times ; thwe months’ At a and at the apex, shallow resorp; P, periodontal membrane ; Rp, shallow tooth. magnifled 8 times; six months’ funcof movement indicated by arrow. C, normal alveolar wall ; pull ; Kn, almost
that ‘physiological treatment’ can under no circumstances be construed to mean any sort of mechanical procedure, regardless of what type of orthodontic appliance is used, and how well it is manipulated and controlled.” For retention t,hese considerations can be disregarded; it is in our power to reduce the possible damages during the retrograde process of transformation to the possible minimum by a proper choice of the appliances used. The pictures of t,he four different stages of retention were taken from the almost intact deciduous incisors of a monkey (baboon) ; two of these
P c A
t&h; two were left without retention so that they rrt,urnrd days to their original position and were subject to full function. were killed after t,hree and six months respectively.
wilhitt it fc\\ ‘PIIF aniiiialh
In Fig. 1 we see a general view picture of a mandibular incisor that ha.tl been rigidly retained for three months aftcar having been mowtl la.bially in At the apex we find minute changes the direction indicated by the arrow. indicative of the beginning process of shedding ((I) ; the lingual sidr is cntirel? Il(r free from resorptions caxwpt for on(l ~ll1Nll al??9 ( It/)) f’0r wliic~h I 1liil.V
545 explanation ; otherwise the cementum is completely intact, particularly in the upper two-thirds of the labial side of pressure (see Fig. 5) ; thus it is evident that the cementum has not been damaged despite the intermittent force and despite t,he formation of osteoid during the intermissions. In the apical area we find no evidence whatever of a deviation of the apex in the direction opposite to the movement of the crown; the tipping took place in such a way that. the apex acted as a fulcrum (see my previous discussion concerning t,he suggested dangers of osteoid and the fulcrum in the first chapter*). In Fig. 5 we see the marginal portion of the labial side of pressure in Fig. 1 (magnification 25 times) ; the bone is wide, and in some areas the perpendicular arrangement of the spicules in the direction of force can still
C D P
Fig.
Fig.
5.
6.
Fig. S.-Marginal portion of the labial sicle of ~~ressul’c: of tooth shown in Fig. 1. magnifled 25 times. Direction of force indicated by arrow ; thwe nzonths’ retention. C. cementum ; arranged in the direction of force. D, dentine ; P, periodontal membrane ; Kn, bone still partly Fig. B.-Marginal portion. of the labial side of pressure of tooth shown in Fig. 2. magnified 25 times ; direction of force indicated by :trrow ; six months’ functional stimulation. C. cementurn: D, dentine; P, periodontal membrane; Kn. transitionxl bone; KNI, osteoid bone. Almost normal lamellous bone structure.
be recognized. The difference in staining between old and new bone is not especially evident in this specimen. I wish to call the new bone which during active orthodontic treatment replaces the original compact bone and is arranged in the direction dictated by the orthodontic appliance transitional bone. In the specimens of retention this transitional bone now represents the “old bone” as compared to the bone which has been newly formed during the period of retention. *INTERNAT.
J. ORTH.
19:
pp.
1208
and
1211,
1933
Ob Krr,
Fig. force root blasts;
7.
i*‘ig, 8.
Fig. i.-Labial sirlr of pressure of tooth shu\\n in Fig. 3 ; nrugrtificatiun 2.5 times ; direction of indicated by arrow : tlzwe month~s fuvcctionnl stimulntio?~. c, comentum ; n, rlentine ; np. resorption; Kn. transitional bone: Km, ostcoid bone: Kw, rachitic boric (?) : Oh, osteoPu,
pulp.
Fig. X.-Labial side of yreisuro of tooth shown in : six vcoratks’ wtcmtimt. Rp, force indicated by arrow transitional bone ; Kn,. osieoid boric : C. cementuni ; I).
IQ’. 4, magnified 23 times ; direction of shallow resurption of ccmentum ; K,tz. dentinc : I’. periodontal membrane.
In Fig. 3 we see a general vielv of a maxillary incisor that has been rnorfvl t,oward the labial side in the directiorl indicated by the arrow. This tctot,h has not been retained and was frilly exposed to functional stimuli. The estensive resorption of t~he apex has in alt probability llothing to do with the possible process of sheddin g and shall be discussed in the subsequent paragraphs. The cementum, which is much t,hickcr on Ihe labial than on the lingual side, is also absolutely intact on the labial side of pressure; no damage (see also has been caused by the osteoid formed dnrin g the intermissions Fig. 7).
Fig. ‘7 illustrates the labial side of pressure in Fig. 3, magnified 25 times. Contrary to the findings in the rigidly retained tooth shown in Fig. 5, there is no more evidence of the previous perpendicular arrangement of the spicules ; the entire labial plate of bone is thinner, the transitional bone (Rn), which can be plainly recognized by the darker staining, is for the most part arranged parallel to the surface of t,he tooth except for two spicules near the alveolar of 100 margin (z, ?j) . This area is reproduced in Fig. 14 in a magnification times and shows the solid fusion of the t,ransitional bone by osteoid bone mhich This extensive formahas been newly formed during the period of retention. tion of osteoid bone along the entire labial wall has not been observed in any ot,her specimen of retention; it may be assumed that this excessive formation
Ob
Ob
c V
P
Fig.
9.
Fig.
10.
Fig. 9.-Marginal portion of the lingual side of pull of tooth shown in Fig. 1, magnified 25 times; direction of force indicated by arrow ;, thwx months’ reteation. C, cementurn; D, membrane ; R~J, resorption dentine ; P, periodontal of cementurn ; f, fusion of neighboring processes of osteoid: ZK, germ of permanent tooth. Fig. lO.-Area A of Fig. 2, magnified 100 times: direction of movement indicated by arrow ; six months’ functional stimulation. C, cementum; D, dentine; P, periodontal membrane; Ob, narKS, transitional bone; KW, osteoid bone surrounded by a dense layer of osteoblasts: rowing the periodontal space; A, fusion of csteoid bone of two adjacent trabeculae.
of osteoid may be due to rickets, caused by captivity. The cementum surface is intact except for some very small, fully repaired defects of the kind which can be found in every normal specimen. On the lingual side of pull the arrangement of the spicules formation of osteoids has taken space is almost closed (directly
(Fig. 3) one can, on the parallel to t,he direction place t,o such an extent above the arrow in Fig.
whole, still recognize of pull ; the excessive that the periodontal 3). Along almost t.he
entire lingual side the fusion of the osttwicl into a IIPW. continnous. inner alveolar wall may be rrcognized. In Fig. 17, illustrating the nrcw ,I iti FiF. 3 magnified 100 times. tbra beginnin, 0’ Inlion of tllr ostroitl bewnlcs wider autl more calcified until it crcatcs a solitl jrinc:tion similar to the oiic that c~o~rttl be fonncl on t,hra labial side in an atiwnwtl stage (SW Fig. 14).
C
Fig. Fig.
Il.--Rhea
A
of
Fig.
11.
Fig. 3, nwgnified
1OU tinles ; stinkulntion. c, cementurr1: I’, t/L?%3 na@vLt1w fulLctiona1 the osteoid of two neighboring trabeculae of bone. Fig. Il.--Arca. A of Fig. 4, lingual side of pull, indicated by arrow; six mcmths retestion. Kn, transitional turn; P, periodontal membranr: z, marked narrow-inp of
12.
ciirociion periodontal
of
furce indicute,.i by arrow : membrane: KTLI, fusion of
magnified XI) times : direction bon:; K?~I. osteoid bone; the periodontal membwne.
of fore? f?. ceme~-
This bone shows on its inner surface evidence of II~~Wformation as a conipensation for the loss of dental structure (Fig. 3 li,z. and Fig. 1:I Ku). \I’c shall refer to this specimen u-hen tlealin g with the In-oblem of root resorption. profnnda” the problem Hiupl’ has tliscnswd in his papw *‘I’aradcntitis of resorption of cementum from wrioiis Grw points ; however, 1 found no necessity to refer to these findings and discussions when dealing with the problem of genuine root resorption, because they hare nothing to do with the shortening of the ilI)Px as described by Ketc?ham. The cwmmotl resorp-
The
C&&s
in
Orthodontia
tions on the lateral portions of the teeth and occasionally at the apex have a well-known etiology, whereas the etiology of genuine root resorption with its characteristic radiographic and histologic picture is still. quite mysterious. A. M. Schwarz tried to explain the etiologic factor for genuine root resorption by the knowledge obtained from the experiments of Gottlieb and Orban on excessive stress, and set down his ideas as established fact.s, although they are mere theories and do not change the fact that the etiology of genuine root resorption is still as mysterious as before, and that genuine root resorption and occasional resorption of the cementum are two entirely different manifestations. I shall discuss this problem later in more detail. In Fig. 4 we see the general view picture of an intact maxillary deciduous incisor that had been moved labially in the direction of the arrow. The tooth
E En
OK
C
P
fig.
13.-aLpex
of
tooth Km,
shown in new bone;
Fig. C,
3, mngnifled cementurn;
P,
100 times. periodontal
OK, osteoclasts membrane.
; K,
solid
bone ;
shows no evidence of beginning shedding. It had been retained rigidly in its labial position for six months. The cementum of the root is absolutely intact in the marginal portion which during the labial movement had been subjected to pressure; no damage has been caused by the osteoid which had been formed during the intermissions (see also Fig. 8, magnification 25 times). Only the upper apical fourth of the labial cementum shows very shallow resorptions of the cementum, which, however, are not located in the area of pressure (Fig. 8 Rp). In Fig. 8 we see the labial side of pressure of Fig. 4 in a magnification of 25 times. In some areas the perpendicular arrangement of the transitional bone (Kn, stained dark) can still be recognized. However, most of the transitional bone is arranged parallel to the surface of the tooth and is
.Ilbi?l
550
op~wtlheir~r.
cc:mpl&ly surrounded by the bone whivll I~as brew newly formrd during thv betwren the two types period of retention (Kw,, light stain 1. ‘Fhr tlifkencr I)olrc~ it n(l thr ur\\-1.1. formcvl bent> of the‘ of bc,nr. namely, t,hr transitional p~riotl of wtfwtion, is vchry prononnwcl ; t,hew teas been no assintilatiorl of clearly in Fig. 15, a these two forms of bon<>, ant1 they can br distilrguishcd 15j. higher magnification of the Arw .I in Fit),. H (Fir. On the lingual side of pull (Fig. 12, iIIffEi *1 of Fig. 1 magnified 80 tinies,J of this t,ootli, tlir direction of pull can still he recognized in some of the spicules The nev- formation of osteoid around the despite six months of retention. transitional bone is wry nmrlred and has in some areas caused a wnsiderable narrowing of the periodontal spaw. But \vc still find in many areas defects forms tilt> lltv irllitJr* slmwlar wali. whrwas in the plate of osteoitl bow \rllicdlt n
P
Kn
Fig. 15.--Area A of Fig. 8. nmgnifled 80 tirlws. six monthu-’ w?tention. C. wrnwtunr : P, periodontal osteoid bone. Notict! th? marked ~lifferrncc bcttwww bone, Km.
Direction membrane transitional
of foucr indicated by arrow; ; Kn. transitional bone ; K?&T, bone. Kn. and nrwlr formed
in the specimens showing the result of three months of functional stimulation (Figs. 3 ant1 11) this regenrrat,ion of the alveolar wall is almost completed. In Fig. 2 we see a genrral view picture of an int,act mandibular deciduous This incisor which had been moved labially in t,he direction of the arrow. tooth shows no evidence of beginning shedding. It, had been released after keatment and was then subjected to full forty days of active orthodontic functional stimulation for six months. The cementum (C) is also completely intact on the labial side of pressure (Figs. 2 and 6) ; it has not been damaged which was formed during the intermissions. by tbt, osteoitl
Just as in the other specimens there are no changes in the apical region which would indicate or suggest any excursion of the apex during the period of active treatment; even though six months have passed since the orthodontic treatment, we should still be able to find evidence of repaired Howship’s lacunae in the bone if such an excursion had taken place. 7%~ not being the case, the asncmption seems justified that the fulcrum was located al the apex. In Fig. 6 we see the marginal portion of the labial side of pressure of Fig. 2 in a magnification of 25 times. During the six months of full functional stimulation the thickness of the bone had been reduced to nearly one-half as compared with Fig. 5 (three months of rigId fixat,ion). The functional struc-
C
Kn
Fig.
16.
Fig.
17.
Direction of force indicated by arrow; of Fig. 6, magnified 100 times. functbnal stimulation. aim wvmths The difference between transitional and new bone which was clearly visible in Fig. 15 cannot be recognized here. C, cementurn; P, periodontal memKm,, osteoid H, Haversian system. brane: Kn, transitional bone; bone; Fig. l’i.-Control tooth, mandibular incisor; labial bone plate showing lamellated structure. Magnification 25 times. C, cementurn; D, dentine; P, pwiodontal membrane; K, bone. Fig.
l&--Area
d
ture of the bone is much more marked in comparison to that shown in Fig. 7 (three mont,hs of full functional stimulation). The labial plate of bone also appears of much more consolidated structure if compared with Fig. 8 (six months of rigid retention) ; it shows almost normal lamellous structure and formation of new Haversian systems (Fig. 16, area A of Fig. 6 magnified 100 times). The distinct difference between transitional and newly formed bone which could be seen in Fig. 8 (six months of rigid retention) has nearly disappeared; there is no longer any difference between the staining of the two types of bone; their assimilation is almost complete, and, as can be seen in
Fig. 16 (six months not retained j in cont,rast to Fig. 15 (six months of rigid retention), the transition of one kind of bone into the other is much more gradual. Sill. rven six months of full fnnctional stimulation have Ilot been suficicni lo tlt3troy this last, remnant of differentiation. On the lingual side of pull of the specimen (Fig. 2. right, sidr. antI Fig. changw art> 10. area A of Fig. 2 magnified 100 Gmrsj tively not, so far advanced as those on the labial siclr: especially near thca alveolar margin t,he first four spicnles of boric arc still arranged in the dirwtion of pull and are not yet fused iiit 0 0x1~’compact new alveolar wa.1I i Fis. 2j but are onI>-, as can be seen in Fig. 10 A. united by narrow bridges of osteoid tissue. The periodontal space is narrowc~tl by cxcessiTe formation of ostrwitl ; the
retropratle
l'tli-
ZK
C P
Fig. Fig. 18.-General shedding. Magnification manent tooth. Fig. lg.--Area periodontal membrane.
view of 10 timcx A
of
Fig-.
Fix:.
1X.
c,ontwl tooth, C, cementurn 18.
Magnification
19.
m;txilluv deciduous incisor ; no evidence ; P, perikdontal nwmbmne : ZK, germ of 2.5 titwts.
C.
cementurn
; 73, dentine
of per;
I’,
below these four spicules of bone the newly formed osteoid forms a c*ontinuous alveolar wall with only occasional breaks. In order to give additional information about t,he extent of the retrograde changes and about the reduction in the thickness of the bone, the corresponding areas of the normal control teeth (maxillary and mandibular incisors) are also reproduced in a magnification of 25 times. In Fig. 17 we see the labial wall of the control tooth, a mandibular incisor, which has been -shown in the first chapter.” The difference in the width of the labial wall of bone between Fig. 5 (three months of retention) and Fig. 6 *INTERNAT.
J. WITH.
19:
1203
(Fig.
l),
1933.
The Crisis in Orthodontia (six months mandibular al comment place, Fig. the normal concerned.
553
not retained), on the one hand, and the labial wall of bone of a control incisor (Fig. 17), on the other hand, without any additiongives a correct idea of the retrograde changes which have taken 6 (six months’ full functional stimulation) more closely resembles condition shown in Fig. 17, as far as the width of the bone is
Fig. 18 shows a general view picture of a maxillary incisor which has been used as the control tooth for the lingual movement shown in the first chapter.” This illustration may serve as additional proof of the intactness There is no evidence of of the deciduous teeth used in these experiments. beginning shedding; the cementum is absolutely intact. Fig. 19 shows area A near the alveolar margin of Fig. 18 magnified 25 times. Here the compact bony wall is not so markedly developed as in the mandible (Fig. 17). The labial bony wall of this tooth (Fig. 8) that had been rigidly retained for six months is still considerably wider than the corresponding area in the control tooth (Fig. 19). The area between points a and b in Fig. 19 may be considered as the normal thickness of the labial alveolar wall. In these specimens all the basic rules and principles of general bone histology and bone pathology are applied to orthodontia for the first time. In summarizing these histologic findings it can be said that: 1. Th.e transformation of bone dwing active orthodontic movement as well as during the period of retention is performed by the activity of bone cells exelusively; this process is by no meaqas a “compensation for a ‘difference in. the tension’ cazcsed by th,e moving of the teeth” (Walkhoff, Skogsborg@). 2. There is a retrograde, process during the period of retention,, the progress of which depends upon, the time which elapses and upon wh,ether or not the tooth
is
retained.
3. This retrograde which
the
artificial
scar 5.
not
functional
stimuli
period of retention 4. This natlsral
the
In
teeth to
bring
canlaot
has
to
as
monkeys ha&
to
process
(such of
act
the
slowly
more
tlaeir
full
rigidly
in
extent;
retained bnce
in
teeth
these
in cases
be e’xtended.
retrograde
formation
the
slcficielzt
process occurs
be improved
cannot
Xkogsborg’s
six
months
origina,
normal
or
stim~ulate&’
by
septotomy), of
fdl
functionnl
stimulation
am
conclitionk
REFERENCES 1. Oppenheim, A.: Die Veranderungen der Gewebe, insbesondere des Enochens bei der Verschiebung der ZLhne, Vrtljschr. f. Zahnheilk. 27: 303, 1911. Tissue Changes, Particularly of the Bone, Incident to Tooth Movement, Am. Ortho. 3: October, 1911; 3: January, 1912. A Study of Bone and Tooth Changes Incident to Experimental Tooth 2. Marshall, J. A.: Movement and Its Application to Orthodontic Practice, INTERNAT J. ORTH. 19: 1, 1933. Die Veranderungen der Gewebe w&rend der Retention, Vrtljschr. f. 3. Oppenheim, A.: Zahnheilk. 29: 325, 1913. 4. Hellman, M.: Physiological Treatment, Dental Cosmos 72: 578, 1930. *INTERNAT.
J. ORTH.
19: 1211
(Fig.
12),
1933.
9
1117 19°F .Y . 11. Itlenr : ’ The Uw of Heptotomy (Surgical Treatment) in Connection With Orthodontic trf Walkhoff’s Theory of Treatment. and the Value of This Method a~ a Proof After Rq~~lation OF Twth. IKTERNAT. .I. ORTHU. 16: Tension of the 13o1re Tissue 1044, 19:I”.
fr,om
pogP
466,
,4pril)
F
because, OR my experiments I hare preferred win, (1 the teeth of monkeys. as I pointed out in 1917.’ their structure is wry similar to that of humarl direct transmisteeth, because the straight course of’ their roots guarantees sion of ort,hodont,ic forces to the bone, and because of the analogous anatomic relations that exist between their teeth and t,he compact a.nd spongy jaw honca and those of man. gives a similar reason for losing rrionke~~s for his experiments: Marshall2 “The teeth of macacus rhesus show certain similarities to the trrth of mm not only in gross and microscopic anatomic: features. . .‘I These same argument,s influenced me also in the seleet,ion of the animals that were wed to study tissue changes (luring rct,rntion. These finclings which were reported briefly in 1913” shall now be reported in a more rxtrnsiw form. The experiment included four teeth and leads through a number of stages of transformation and retrograde changes back almost to the original lamellous bony structure. The following description of the ret rogratlr changes in the bone tlurill~ the period of retention Aarts out with the arrangement of t,he hone which is the result, of gent,le intermittent. forces as described in thv first chapter of t,his paper.$ Just as in this previous report I am showing first a general view picture of each one of t~he mored deciduous t,reth to illustrate the validity of findings in intact deciduous te&h ; by illustrating a control tooth and by using a uniform magnification (25 times) for wrrrsponding specimens, it ih possible to study the retrograde transformation during t,he period of retelltion and t,he narrowing of the bone which had been widened durirlg the periotl of active movement, by a new formation of ostcoplrytes. This gra.dual narrowing and functional transformation of the bone (‘an be plainly seen on teeth that have been retained rigidly as well as on teeth which have been subject lo the full influence of function ; however. we shall see that the extent of tjhcse changes depends largelyupon the degree of functional st.imulus. Jn jnimobilizetl. rigitlty rrtainetl trctlr the retrogratle *From the Department of Orthodontia of the tTranslated from Zeitsclw@t fiir GtomntoEo~gic. Schwarzenberg, Vienna and Berlin. ~INTmN.~T. J. ORTH. I!): 1206 (Fig. 6 ), l!l:I::. 5-1”
Dental Nos.
Institute of the CTniveraity 7 and 8, 1933, published by
of Vienna. Tirban and
transformation is less extensive than in teeth that have been subject to funct.ional stimulation. This process of transformation leads from the arrangemeat of the trabeculae parallel to the direction of force back to the arrangement parallel to the long axis of the tooth with lamellated structure of the bone and new Haversian canals. These pictures are very instructive, since the changes during retention are governed by individual requirements and endogenous forces and not by any ot,her influences or exogenous forces. As I stated in the first chapter, each active influence exerted upon the bone by means of appliances produces only relative biologic changes. This “It may be saitl has also been clearly recognized and laid down by IIellman:4
A
RP C C P %E
a
Fig. Fig.
1.
I.-General view picture of mandibular incisor wrtelztion. Direction of movement indicated by arrow. tions due perhaps to beginning shedding. C, cementurn resorption on the lingual side; ZK, germ of permanent Fig. S.-General view picture of mandibular incisor, tional stimulatiw. No evidence of shedding: direction cementurn ; A, osteoid bone, arranged in the direction of LK, germ of permanent tooth.
Fig.
2.
; magnification 8 times ; thwe months’ At a and at the apex, shallow resorp; P, periodontal membrane ; Rp, shallow tooth. magnifled 8 times; six months’ funcof movement indicated by arrow. C, normal alveolar wall ; pull ; Kn, almost
that ‘physiological treatment’ can under no circumstances be construed to mean any sort of mechanical procedure, regardless of what type of orthodontic appliance is used, and how well it is manipulated and controlled.” For retention t,hese considerations can be disregarded; it is in our power to reduce the possible damages during the retrograde process of transformation to the possible minimum by a proper choice of the appliances used. The pictures of t,he four different stages of retention were taken from the almost intact deciduous incisors of a monkey (baboon) ; two of these
P c A
t&h; two were left without retention so that they rrt,urnrd days to their original position and were subject to full function. were killed after t,hree and six months respectively.
wilhitt it fc\\ ‘PIIF aniiiialh
In Fig. 1 we see a general view picture of a mandibular incisor that ha.tl been rigidly retained for three months aftcar having been mowtl la.bially in At the apex we find minute changes the direction indicated by the arrow. indicative of the beginning process of shedding ((I) ; the lingual sidr is cntirel? Il(r free from resorptions caxwpt for on(l ~ll1Nll al??9 ( It/)) f’0r wliic~h I 1liil.V
545 explanation ; otherwise the cementum is completely intact, particularly in the upper two-thirds of the labial side of pressure (see Fig. 5) ; thus it is evident that the cementum has not been damaged despite the intermittent force and despite t,he formation of osteoid during the intermissions. In the apical area we find no evidence whatever of a deviation of the apex in the direction opposite to the movement of the crown; the tipping took place in such a way that. the apex acted as a fulcrum (see my previous discussion concerning t,he suggested dangers of osteoid and the fulcrum in the first chapter*). In Fig. 5 we see the marginal portion of the labial side of pressure in Fig. 1 (magnification 25 times) ; the bone is wide, and in some areas the perpendicular arrangement of the spicules in the direction of force can still
C D P
Fig.
Fig.
5.
6.
Fig. S.-Marginal portion of the labial sicle of ~~ressul’c: of tooth shown in Fig. 1. magnifled 25 times. Direction of force indicated by arrow ; thwe nzonths’ retention. C. cementum ; arranged in the direction of force. D, dentine ; P, periodontal membrane ; Kn, bone still partly Fig. B.-Marginal portion. of the labial side of pressure of tooth shown in Fig. 2. magnified 25 times ; direction of force indicated by :trrow ; six months’ functional stimulation. C. cementurn: D, dentine; P, periodontal membrane; Kn. transitionxl bone; KNI, osteoid bone. Almost normal lamellous bone structure.
be recognized. The difference in staining between old and new bone is not especially evident in this specimen. I wish to call the new bone which during active orthodontic treatment replaces the original compact bone and is arranged in the direction dictated by the orthodontic appliance transitional bone. In the specimens of retention this transitional bone now represents the “old bone” as compared to the bone which has been newly formed during the period of retention. *INTERNAT.
J. ORTH.
19:
pp.
1208
and
1211,
1933
Ob Krr,
Fig. force root blasts;
7.
i*‘ig, 8.
Fig. i.-Labial sirlr of pressure of tooth shu\\n in Fig. 3 ; nrugrtificatiun 2.5 times ; direction of indicated by arrow : tlzwe month~s fuvcctionnl stimulntio?~. c, comentum ; n, rlentine ; np. resorption; Kn. transitional bone: Km, ostcoid bone: Kw, rachitic boric (?) : Oh, osteoPu,
pulp.
Fig. X.-Labial side of yreisuro of tooth shown in : six vcoratks’ wtcmtimt. Rp, force indicated by arrow transitional bone ; Kn,. osieoid boric : C. cementuni ; I).
IQ’. 4, magnified 23 times ; direction of shallow resurption of ccmentum ; K,tz. dentinc : I’. periodontal membrane.
In Fig. 3 we see a general vielv of a maxillary incisor that has been rnorfvl t,oward the labial side in the directiorl indicated by the arrow. This tctot,h has not been retained and was frilly exposed to functional stimuli. The estensive resorption of t~he apex has in alt probability llothing to do with the possible process of sheddin g and shall be discussed in the subsequent paragraphs. The cementum, which is much t,hickcr on Ihe labial than on the lingual side, is also absolutely intact on the labial side of pressure; no damage (see also has been caused by the osteoid formed dnrin g the intermissions Fig. 7).
Fig. ‘7 illustrates the labial side of pressure in Fig. 3, magnified 25 times. Contrary to the findings in the rigidly retained tooth shown in Fig. 5, there is no more evidence of the previous perpendicular arrangement of the spicules ; the entire labial plate of bone is thinner, the transitional bone (Rn), which can be plainly recognized by the darker staining, is for the most part arranged parallel to the surface of t,he tooth except for two spicules near the alveolar of 100 margin (z, ?j) . This area is reproduced in Fig. 14 in a magnification times and shows the solid fusion of the t,ransitional bone by osteoid bone mhich This extensive formahas been newly formed during the period of retention. tion of osteoid bone along the entire labial wall has not been observed in any ot,her specimen of retention; it may be assumed that this excessive formation
Ob
Ob
c V
P
Fig.
9.
Fig.
10.
Fig. 9.-Marginal portion of the lingual side of pull of tooth shown in Fig. 1, magnified 25 times; direction of force indicated by arrow ;, thwx months’ reteation. C, cementurn; D, membrane ; R~J, resorption dentine ; P, periodontal of cementurn ; f, fusion of neighboring processes of osteoid: ZK, germ of permanent tooth. Fig. lO.-Area A of Fig. 2, magnified 100 times: direction of movement indicated by arrow ; six months’ functional stimulation. C, cementum; D, dentine; P, periodontal membrane; Ob, narKS, transitional bone; KW, osteoid bone surrounded by a dense layer of osteoblasts: rowing the periodontal space; A, fusion of csteoid bone of two adjacent trabeculae.
of osteoid may be due to rickets, caused by captivity. The cementum surface is intact except for some very small, fully repaired defects of the kind which can be found in every normal specimen. On the lingual side of pull the arrangement of the spicules formation of osteoids has taken space is almost closed (directly
(Fig. 3) one can, on the parallel to t,he direction place t,o such an extent above the arrow in Fig.
whole, still recognize of pull ; the excessive that the periodontal 3). Along almost t.he
entire lingual side the fusion of the osttwicl into a IIPW. continnous. inner alveolar wall may be rrcognized. In Fig. 17, illustrating the nrcw ,I iti FiF. 3 magnified 100 times. tbra beginnin, 0’ Inlion of tllr ostroitl bewnlcs wider autl more calcified until it crcatcs a solitl jrinc:tion similar to the oiic that c~o~rttl be fonncl on t,hra labial side in an atiwnwtl stage (SW Fig. 14).
C
Fig. Fig.
Il.--Rhea
A
of
Fig.
11.
Fig. 3, nwgnified
1OU tinles ; stinkulntion. c, cementurr1: I’, t/L?%3 na@vLt1w fulLctiona1 the osteoid of two neighboring trabeculae of bone. Fig. Il.--Arca. A of Fig. 4, lingual side of pull, indicated by arrow; six mcmths retestion. Kn, transitional turn; P, periodontal membranr: z, marked narrow-inp of
12.
ciirociion periodontal
of
furce indicute,.i by arrow : membrane: KTLI, fusion of
magnified XI) times : direction bon:; K?~I. osteoid bone; the periodontal membwne.
of fore? f?. ceme~-
This bone shows on its inner surface evidence of II~~Wformation as a conipensation for the loss of dental structure (Fig. 3 li,z. and Fig. 1:I Ku). \I’c shall refer to this specimen u-hen tlealin g with the In-oblem of root resorption. profnnda” the problem Hiupl’ has tliscnswd in his papw *‘I’aradcntitis of resorption of cementum from wrioiis Grw points ; however, 1 found no necessity to refer to these findings and discussions when dealing with the problem of genuine root resorption, because they hare nothing to do with the shortening of the ilI)Px as described by Ketc?ham. The cwmmotl resorp-
The
C&&s
in
Orthodontia
tions on the lateral portions of the teeth and occasionally at the apex have a well-known etiology, whereas the etiology of genuine root resorption with its characteristic radiographic and histologic picture is still. quite mysterious. A. M. Schwarz tried to explain the etiologic factor for genuine root resorption by the knowledge obtained from the experiments of Gottlieb and Orban on excessive stress, and set down his ideas as established fact.s, although they are mere theories and do not change the fact that the etiology of genuine root resorption is still as mysterious as before, and that genuine root resorption and occasional resorption of the cementum are two entirely different manifestations. I shall discuss this problem later in more detail. In Fig. 4 we see the general view picture of an intact maxillary deciduous incisor that had been moved labially in the direction of the arrow. The tooth
E En
OK
C
P
fig.
13.-aLpex
of
tooth Km,
shown in new bone;
Fig. C,
3, mngnifled cementurn;
P,
100 times. periodontal
OK, osteoclasts membrane.
; K,
solid
bone ;
shows no evidence of beginning shedding. It had been retained rigidly in its labial position for six months. The cementum of the root is absolutely intact in the marginal portion which during the labial movement had been subjected to pressure; no damage has been caused by the osteoid which had been formed during the intermissions (see also Fig. 8, magnification 25 times). Only the upper apical fourth of the labial cementum shows very shallow resorptions of the cementum, which, however, are not located in the area of pressure (Fig. 8 Rp). In Fig. 8 we see the labial side of pressure of Fig. 4 in a magnification of 25 times. In some areas the perpendicular arrangement of the transitional bone (Kn, stained dark) can still be recognized. However, most of the transitional bone is arranged parallel to the surface of the tooth and is
.Ilbi?l
550
op~wtlheir~r.
cc:mpl&ly surrounded by the bone whivll I~as brew newly formrd during thv betwren the two types period of retention (Kw,, light stain 1. ‘Fhr tlifkencr I)olrc~ it n(l thr ur\\-1.1. formcvl bent> of the‘ of bc,nr. namely, t,hr transitional p~riotl of wtfwtion, is vchry prononnwcl ; t,hew teas been no assintilatiorl of clearly in Fig. 15, a these two forms of bon<>, ant1 they can br distilrguishcd 15j. higher magnification of the Arw .I in Fit),. H (Fir. On the lingual side of pull (Fig. 12, iIIffEi *1 of Fig. 1 magnified 80 tinies,J of this t,ootli, tlir direction of pull can still he recognized in some of the spicules The nev- formation of osteoid around the despite six months of retention. transitional bone is wry nmrlred and has in some areas caused a wnsiderable narrowing of the periodontal spaw. But \vc still find in many areas defects forms tilt> lltv irllitJr* slmwlar wali. whrwas in the plate of osteoitl bow \rllicdlt n
P
Kn
Fig. 15.--Area A of Fig. 8. nmgnifled 80 tirlws. six monthu-’ w?tention. C. wrnwtunr : P, periodontal osteoid bone. Notict! th? marked ~lifferrncc bcttwww bone, Km.
Direction membrane transitional
of foucr indicated by arrow; ; Kn. transitional bone ; K?&T, bone. Kn. and nrwlr formed
in the specimens showing the result of three months of functional stimulation (Figs. 3 ant1 11) this regenrrat,ion of the alveolar wall is almost completed. In Fig. 2 we see a genrral view picture of an int,act mandibular deciduous This incisor which had been moved labially in t,he direction of the arrow. tooth shows no evidence of beginning shedding. It, had been released after keatment and was then subjected to full forty days of active orthodontic functional stimulation for six months. The cementum (C) is also completely intact on the labial side of pressure (Figs. 2 and 6) ; it has not been damaged which was formed during the intermissions. by tbt, osteoitl
Just as in the other specimens there are no changes in the apical region which would indicate or suggest any excursion of the apex during the period of active treatment; even though six months have passed since the orthodontic treatment, we should still be able to find evidence of repaired Howship’s lacunae in the bone if such an excursion had taken place. 7%~ not being the case, the asncmption seems justified that the fulcrum was located al the apex. In Fig. 6 we see the marginal portion of the labial side of pressure of Fig. 2 in a magnification of 25 times. During the six months of full functional stimulation the thickness of the bone had been reduced to nearly one-half as compared with Fig. 5 (three months of rigId fixat,ion). The functional struc-
C
Kn
Fig.
16.
Fig.
17.
Direction of force indicated by arrow; of Fig. 6, magnified 100 times. functbnal stimulation. aim wvmths The difference between transitional and new bone which was clearly visible in Fig. 15 cannot be recognized here. C, cementurn; P, periodontal memKm,, osteoid H, Haversian system. brane: Kn, transitional bone; bone; Fig. l’i.-Control tooth, mandibular incisor; labial bone plate showing lamellated structure. Magnification 25 times. C, cementurn; D, dentine; P, pwiodontal membrane; K, bone. Fig.
l&--Area
d
ture of the bone is much more marked in comparison to that shown in Fig. 7 (three mont,hs of full functional stimulation). The labial plate of bone also appears of much more consolidated structure if compared with Fig. 8 (six months of rigid retention) ; it shows almost normal lamellous structure and formation of new Haversian systems (Fig. 16, area A of Fig. 6 magnified 100 times). The distinct difference between transitional and newly formed bone which could be seen in Fig. 8 (six months of rigid retention) has nearly disappeared; there is no longer any difference between the staining of the two types of bone; their assimilation is almost complete, and, as can be seen in
Fig. 16 (six months not retained j in cont,rast to Fig. 15 (six months of rigid retention), the transition of one kind of bone into the other is much more gradual. Sill. rven six months of full fnnctional stimulation have Ilot been suficicni lo tlt3troy this last, remnant of differentiation. On the lingual side of pull of the specimen (Fig. 2. right, sidr. antI Fig. changw art> 10. area A of Fig. 2 magnified 100 Gmrsj tively not, so far advanced as those on the labial siclr: especially near thca alveolar margin t,he first four spicnles of boric arc still arranged in the dirwtion of pull and are not yet fused iiit 0 0x1~’compact new alveolar wa.1I i Fis. 2j but are onI>-, as can be seen in Fig. 10 A. united by narrow bridges of osteoid tissue. The periodontal space is narrowc~tl by cxcessiTe formation of ostrwitl ; the
retropratle
l'tli-
ZK
C P
Fig. Fig. 18.-General shedding. Magnification manent tooth. Fig. lg.--Area periodontal membrane.
view of 10 timcx A
of
Fig-.
Fix:.
1X.
c,ontwl tooth, C, cementurn 18.
Magnification
19.
m;txilluv deciduous incisor ; no evidence ; P, perikdontal nwmbmne : ZK, germ of 2.5 titwts.
C.
cementurn
; 73, dentine
of per;
I’,
below these four spicules of bone the newly formed osteoid forms a c*ontinuous alveolar wall with only occasional breaks. In order to give additional information about t,he extent of the retrograde changes and about the reduction in the thickness of the bone, the corresponding areas of the normal control teeth (maxillary and mandibular incisors) are also reproduced in a magnification of 25 times. In Fig. 17 we see the labial wall of the control tooth, a mandibular incisor, which has been -shown in the first chapter.” The difference in the width of the labial wall of bone between Fig. 5 (three months of retention) and Fig. 6 *INTERNAT.
J. WITH.
19:
1203
(Fig.
l),
1933.
The Crisis in Orthodontia (six months mandibular al comment place, Fig. the normal concerned.
553
not retained), on the one hand, and the labial wall of bone of a control incisor (Fig. 17), on the other hand, without any additiongives a correct idea of the retrograde changes which have taken 6 (six months’ full functional stimulation) more closely resembles condition shown in Fig. 17, as far as the width of the bone is
Fig. 18 shows a general view picture of a maxillary incisor which has been used as the control tooth for the lingual movement shown in the first chapter.” This illustration may serve as additional proof of the intactness There is no evidence of of the deciduous teeth used in these experiments. beginning shedding; the cementum is absolutely intact. Fig. 19 shows area A near the alveolar margin of Fig. 18 magnified 25 times. Here the compact bony wall is not so markedly developed as in the mandible (Fig. 17). The labial bony wall of this tooth (Fig. 8) that had been rigidly retained for six months is still considerably wider than the corresponding area in the control tooth (Fig. 19). The area between points a and b in Fig. 19 may be considered as the normal thickness of the labial alveolar wall. In these specimens all the basic rules and principles of general bone histology and bone pathology are applied to orthodontia for the first time. In summarizing these histologic findings it can be said that: 1. Th.e transformation of bone dwing active orthodontic movement as well as during the period of retention is performed by the activity of bone cells exelusively; this process is by no meaqas a “compensation for a ‘difference in. the tension’ cazcsed by th,e moving of the teeth” (Walkhoff, Skogsborg@). 2. There is a retrograde, process during the period of retention,, the progress of which depends upon, the time which elapses and upon wh,ether or not the tooth
is
retained.
3. This retrograde which
the
artificial
scar 5.
not
functional
stimuli
period of retention 4. This natlsral
the
In
teeth to
bring
canlaot
has
to
as
monkeys ha&
to
process
(such of
act
the
slowly
more
tlaeir
full
rigidly
in
extent;
retained bnce
in
teeth
these
in cases
be e’xtended.
retrograde
formation
the
slcficielzt
process occurs
be improved
cannot
Xkogsborg’s
six
months
origina,
normal
or
stim~ulate&’
by
septotomy), of
fdl
functionnl
stimulation
am
conclitionk
REFERENCES 1. Oppenheim, A.: Die Veranderungen der Gewebe, insbesondere des Enochens bei der Verschiebung der ZLhne, Vrtljschr. f. Zahnheilk. 27: 303, 1911. Tissue Changes, Particularly of the Bone, Incident to Tooth Movement, Am. Ortho. 3: October, 1911; 3: January, 1912. A Study of Bone and Tooth Changes Incident to Experimental Tooth 2. Marshall, J. A.: Movement and Its Application to Orthodontic Practice, INTERNAT J. ORTH. 19: 1, 1933. Die Veranderungen der Gewebe w&rend der Retention, Vrtljschr. f. 3. Oppenheim, A.: Zahnheilk. 29: 325, 1913. 4. Hellman, M.: Physiological Treatment, Dental Cosmos 72: 578, 1930. *INTERNAT.
J. ORTH.
19: 1211
(Fig.
12),
1933.
9
1117 19°F .Y . 11. Itlenr : ’ The Uw of Heptotomy (Surgical Treatment) in Connection With Orthodontic trf Walkhoff’s Theory of Treatment. and the Value of This Method a~ a Proof After Rq~~lation OF Twth. IKTERNAT. .I. ORTHU. 16: Tension of the 13o1re Tissue 1044, 19:I”.